Chemical Structure of Conductive Filaments in Tantalum Oxide Memristive Devices and Its Implications for the Formation Mechanism

Resistive switching in metal oxides is believed to be caused by a temperature and electric field driven redistribution of oxygen vacancies within nanometer sized conductive filament. Accordingly, gaining detailed information about the chemical composition filaments key importance for comprehensive understanding process. In this work, spectromicroscopy used probe electronic structure Ta2O5-based memristive devices. It found that resistive leads formation filament with an vacancy concentration ≈20%. Spectroscopic insights provide state tantalum cations show not composed metallic Ta0 phase. As extreme case, devices after irreversible dielectric breakdown are investigated. These feature larger channels higher concentrations. Using experimental data as input finite element simulations, role thermodiffusion process revealed. demonstrated dominating effect here but might play accelerating forming process, well stabilization